Studies have shown that the addition of biochar to agricultural soils has the potential to mitigate climate change by decreasing nitrous oxide (N₂O) emissions resulting from denitrification. Rice paddy field soils have been known to have strong denitrifying activity, but the response of microbes to biochar for weakening denitrification in rice paddy field soils is not well known. In this work, compared with the chemical fertilizer alone, the chemical fertilizer + 20 t hm⁻² biochar fertilizer slightly decreased denitrifying the nitrite reductase activity (S-NiR) and N₂O emission without statistic difference, whereas the chemical fertilizer + 40 t hm⁻² biochar significantly boosted them. The abundance of nir-denitrifiers contributed to S-NiR and N₂O emission, especially nirS-denitrifiers, rather than the variation of community structure. Pearson correlation analysis showed that NO₂⁻-N was a key factor for controlling the abundance of nir-denitrifiers, S-NiR and N₂O emission. The biochar addition fertilization treatments strongly shaped the community structure of nirK-denitrifiers, while the community structure of nirS-denitrifiers remained relatively stable. In addition, Paracoccus and Sinorhizobium were revealed to be as the predominant lineage of nirS- and nirK-containing denitrifiers, respectively. Distance-based redundancy analysis (db-RDA) showed that changes in the nir-denitrifier community structure were significantly related to soil organic carbon, NO₃⁻-N, and total phosphorus. Our findings suggest that, although the nirS- and nirK-denitrifiers are both controlling nitrite reductase, their responses to biochar addition fertilization treatments showed significant discrepancies of diversity, abundance, and contribution to N₂O and S-NiR in a paddy soil.

研究表明，在农业土壤中添加生物碳有可能通过减少反硝化产生的一氧化二氮（N ₂ O）排放来缓解气候变化。已知稻田土壤具有强的反硝化活性，但是对于稻田土壤中微生物对生物炭的反应，以减弱其反硝化作用尚不为人所知。在这项工作中，与单独使用化肥相比，化学肥料+ 20 t hm ^-2生物炭肥料略有降低，反硝化亚硝酸还原酶活性（S-NiR）和N ₂ O排放量无统计学差异，而化学肥料+ 40 t hm ^-2生物炭显着促进了它们的生长。大量的尼尔-脱氮剂有助于S-NiR和N ₂ O的排放，尤其是nirS-脱氮剂，而不是群落结构的变化。皮尔逊相关分析表明，NO ₂ ^-- N是控制nir-脱氮剂，S-NiR和N ₂ O排放量的关键因素。生物炭除了施肥极力塑造的群落结构nirK -denitrifiers，而社会结构NIRS -denitrifiers保持相对稳定。此外，副球菌和中华根瘤菌被发现是nirS的主要血统-和分别包含nirK的反硝化剂。基于距离的冗余度分析（db-RDA）表明，nir-反硝化剂群落结构的变化与土壤有机碳，NO ₃ ^-- N和总磷显着相关。我们的研究结果表明，尽管nirS-和nirK-脱氮剂均控制亚硝酸还原酶，但它们对生物炭添加施肥处理的反应显示出稻田土壤中多样性，丰度以及对N ₂ O和S-NiR的贡献存在明显差异。